Obstructive sleep apnea (OSA) is a common medical disorder that can be quite serious. It has been reported that approximately one in twenty-two Americans (about 12,000,000 people) suffer from OSA, and many cases go undiagnosed. Chronic fatigue has long been recognized as the hallmark of OSA, but more recently, large clinical studies have shown a strong link between OSA, strokes and death.
Obstructive sleep apnea is a condition in which the flow of air pauses or decreases during breathing while one is asleep, because the airway has become narrowed, blocked, or floppy. A pause in breathing is called an apnea episode, while a decrease in airflow during breathing is called a hypopnea episode. Almost everyone has brief apnea or hypopnea episodes while they sleep. In OSA, however, apnea episodes occur more frequently and last longer than in the general population. OSA has become an increasingly costly medical condition in recent years, as the disorder is more prevalent in obese people and obesity has become significantly more prevalent. Unfortunately, the currently available options for treating OSA are not ideal.
A person with OSA usually begins snoring heavily soon after falling asleep. Often the snoring gets louder. The snoring is then interrupted by a long silent period during which there is no breathing. This is followed by a loud snort and gasp, as the person attempts to breathe. This pattern repeats. Many people wake up unrefreshed in the morning and feel sleepy or drowsy throughout the day. This is called excessive daytime sleepiness (EDS). People with sleep apnea may act grumpy or irritable, be forgetful, fall asleep while working, reading, or watching TV, feel sleepy or even fall asleep while driving, or have hard-to-treat headaches. OSA sufferers may also experience depression that becomes worse, hyperactive behavior (especially in children), or leg swelling (if severe).
The most widely used therapy for OSA is Continuous Positive Airway Pressure (CPAP). A CPAP system typically consists of a mask fitting in or over the nose or nose and mouth, an air pressurizing console (or blower) and a hose connecting the two (typically a six-foot long hose with a 20 mm diameter bore). CPAP works by pressurizing the upper airway throughout the breathing cycle, essentially inflating the airway to keep it open and thus creating what is sometimes referred to as a “pneumatic splint.” This flow is at set pressure that has been predetermined through medical testing to be appropriate to create a pneumatic splint in the user's airway. This prevents airway collapse and allows the user to breath without obstruction. Because the masks typically leak air, CPAP systems have to provide an airflow rate of up to 200 liters per minute (approximate figure based on unpublished data). The high airflow rate is needed for multiple reasons. First, all the air needed for breathing must come through the hose. Second, conventional masks have an intended leak built in for the purpose of constant “CO2 washout.” Third, these systems achieve the required pressure by using a high airflow rate to generate a back-pressure at the mask end where the air is leaking out. Unfortunately, this high flow rate makes breathing feel quite uncomfortable for many users and requires a relatively large, noisy blower. Additionally, the high required flow rates of CPAP often cause discomfort during exhalation due to increased resistance, as well as nasal dryness, dry mouth, ear pain, rhinitis, abdominal bloating and headaches.
The overwhelming shortcoming of CPAP is poor user compliance. Over half of all users who try CPAP stop using it. Users dislike the side effects mentioned above, as well as having to wear an uncomfortable, claustrophobic mask, being tethered to a pressurizing console, the noise of the console, traveling with a bulky device, and a loss of personal space in bed.
Many CPAP devices and alternatives to CPAP have been developed, but all have significant shortcomings. Less invasive attempts at OSA treatment, such as behavior modification, sleep positioning and removable splints to be worn in the mouth, rarely work. A number of different surgical approaches for treating OSA have also been tried, some of which are still in use. For example, Uvulopalatopharyngoplasty (UPPP) and Laser Assisted Uvula Palatoplasty (LAUP) are currently used. Surgical approaches, however, are often quite invasive and not always effective at treating OSA.
One alternative approach to OSA treatment is to provide a pneumatic splint during the expiratory portion of the respiratory cycle by producing a partial blockage in the nose or mouth, thus slowing the release of air during expiration and increasing positive pressure in the airway. The simplest way to form an expiratory pneumatic splint, pursing the lips, has been shown to open the upper airway and improve breathing in emphysema users. This type of maneuver is generically labeled Expiratory Positive Airway Pressure (EPAP).
Therefore, it would be advantageous to have improved systems, devices and methods for treating OSA and snoring. Ideally, such systems, devices and methods would be less cumbersome than currently available CPAP systems, to improve user compliance. Also ideally, such systems, devices and methods would provide some of the advantages of an expiratory pneumatic splint. At least some of these objectives were met by the embodiments described in references listed above and incorporated herein by reference.
While these references are an important improvement over the state of the art, it would be advantageous to improve upon these systems by making the system simpler and more compact in design, simpler to use, and more robust.